Description: To address the need for low-ballistic coefficient aeroshells with minimal impact on vehicle weight, NASA is investigating flexible thermal protection system (TPS) options. These designs typically consist of a flexible three-directional (3D) woven carbon cloth that can be stowed during flight and deployed on command to serve as a semi-rigid aeroshell during atmospheric entry. For some planned entry trajectories, the woven TPS is subjected to short duration, but extremely high heat flux levels. Since current plans call for the use of as-received non-heat treated carbon fibers in the WTPS, MR&D aims to investigate whether exposure to high temperature, short duration temperatures alters the graphitic microstructure and thus the properties of PAN-based carbon fibers.

Benefits: The program would directly benefit the ADEPT program as well as the Woven TPS program, which are currently focused on the use of 3D weaves in ablative TPS. The increased ability that predictive tools will gain from this program will allow the evaluation of multiple design configurations and fiber types in a much more efficient and cost effective manner than having to fabricate and test panels to generate data to be used for down-selection of the best candidate designs.

There is also potential for applications within the Department of Defense (DoD) and commercial industry. The use of 2D fabrics and 3D woven preforms in carbon-carbon composites which heat treat the reinforcement during processing, instead of beforehand in batch or line heat treat furnaces, creates a need for the predictive modeling capabilities proposed herein.